Elevator group supervisory control system

ABSTRACT

The disclosure relates to an elevator group supervisory control system in which bits of information, as to registered demands for service, position of the cars, and the degree of availability of the cars relative to the number of calls for service each is capable of answering without undue delay, are successively and repetitively scanned to control the respective movement of the cars.

United States Patent [72] Inventor John Gingrich 3,443,668 5/1969 Hallet a1, 187/29 Toronto, Canada 2,827,981 3/1958 Eames et al.. 187/29 [21]Appl 592186 2,960,187 11/1960 Bruns et al... 187/29 [22] Filed No 4,19663,080,944 3/1963 Burgy et a1 187/29 [45] Patented Feb 9.197] 3,146,8589/1964 Leroux et al..., 187/29 [73] Assignee Dover Corporation 3,315,7654/1967 Dinning 1, 187/29 New York, 3,376,952 4/1968 lnuzuka et a1.187/29 by mesne assignments 3,378,107 4/1968 Madison 187/29 [32]Priority Nov. 5,1965 3,379,284 4/1968 Yeastmg v 187/29 1 Great BritainPrimary Examiner-Cris L. Rader [31] 47,065 Assistant ExaminerW. E.Duncanson,lr.

Artorney-Brumbaugh, Free, Graves & Donohue [54] ELEVATOR GROUPSUPERVISORY CONTROL SYSTEM 54 Claims, 50 Drawing Figs.

U-S. The disclosure relates to an elevator group Su. Cl B661) pervisorycontrol system in which bits ofinformation, as to reofSearch V gi tereddemands for ervice position of the cars and the degree of availabilityofthe cars relative to the number of calls [56] References cued forservice each is capable of answering without undue delay, UNITED STATESPATENTS are successively and repetitively scanned to control the3,371,747 3/1968 Gingrich et a1. 187/29 respective movement ofthe cars.

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1. In an elevatoR system comprising a plurality of elevator cars servinga plurality of floors, car position means controlled by the positions ofsaid cars, call registering means for registering calls for service bysaid cars for said floors, means for successively and repetitivelyscanning on a continuous basis said call registering means and saidposition means, controlling means responsive to said scanning means forcontrolling the movement of at least one of said cars dependent upon therelative positions of said calls to said cars, further comprisingpassenger responsive means for each car operable by the passengers in acar, direction means for each car controlled by the direction ofmovement for which a car is available to move, and means for indicatingthe degree of availability of each car relative to the number of callsfor service it is capable of answering without undue delay controlled bysaid passenger responsive means and said direction means, and whereinsaid scanning means also scans said availability means and saidcontrolling means controls the movement of said cars and selectivelycauses a car to answer hall calls dependent upon the condition of saidavailability means and the number and location of said hall calls inrelation to said last-mentioned car and to said other cars.
 2. Forup-peak traffic when: a. there are less than a predetermined number ofdown hall calls, said last-mentioned number being no greater than thepredetermined number is subparagraph 1a hereof; b. the total hall callshave a predetermined relation to the sum of the car availability numbersdifferent from that for down-peak; and c. the ratio of the rate of carstops for car calls to the rate of car stops for down hall calls is atleast equal to said predetermined value in subparagraph 1c hereof.
 2. Asystem as set forth in claim 1 wherein said passenger responsive meanscomprises weighing means for weighing the load in a car and saidavailability indicating means has a first and a second condition whensaid load is respectively less than and at least a predetermined value.2. means for selecting up trip cars in a predetermined order to beup-peak ''''special'''' and up-peak ''''normal'''' cars, and
 2. in thedown direction to said car, the up hall calls and availability numbersfor cars above said car;
 2. in a direction toward a car, the hall callsfor service in a second direction and the availability numberS of carsin said away direction;
 2. preferential service away from said mainfloor when: a. there are less than a predetermined number of down hallcalls, said last-mentioned number being no greater than thepredetermined number in subparagraph 1a hereof; b. the total hall callshave a predetermined relation to the sum of the car availability numbersdifferent from that in subparagraph 1b. hereof; and c. said ratio of therate of car stops for car calls to the rate of car stops for down hallcalls is at least equal to said predetermined value set forth inparagraph 1c hereof.
 2. said answering car is down-available and thescanning shows that there is a down hall call below said answering carand there is no other down-available car between said answering car andthe last-mentioned call; or
 2. availability number N-C: car available tomove up or down and there is a number C of car calls registered for afloor or floors between the car and the floor of the next registeredhall call in the direction in which the caR is available to move,wherein C is less than N and greater than O; and
 3. availability numberO and unavailable: a. car directionally available to move up or down butthe number of registered car calls for a floor or floors between the carand the floor of the next registered hall call in the direction in whichthe car is available to move is equal to or greater than N; b. carunavailable, being out of service, or not available to move in thedirection of a registered hall call or calls means for repetitivelyscanning on a continuous basis with respect to each car said hall callregistering means and said availability means, and dispatching meansresponsive to said scanning means for directing an answering car toanswer registered hall calls whenever:
 3. the scanning shows, withrespect to said answering car, that the number of scanned hall callsabove said answering car has a predetermined relation to the sum of theavailability numbers corresponding corresponding to the availabilitymeans theretofore scanned for other cars located above said answeringcar; or
 3. in a direction away from a car, opposite to the directionaway from the car set forth in (1), the hall calls for service in saidsecond direction and the availability numbers of cars in said awaydirection first-mentioned in this subparagraph (3);
 3. in the downdirection below said car, the up hall calls and availability numbers forcars below said car;
 3. means for preventing down bound, up-peak''''special'''' cars from reversing direction before travelling to themain floor and from stopping to answer more than a predetermined numberof down hall calls.
 3. A system as set forth in claim 1 wherein saidpassenger responsive means comprises weighing means for weighing theload in a car and said availability indicating means has a firstcondition when said load is less than a first predetermined value, asecond condition when said load is at least equal to said firstpredetermined value but less than a second predetermined value and athird condition when said load is at least equal to said secondpredetermined value.
 4. A system as set forth in claim 2 wherein saidpassenger responsive means also comprises car call registering means ineach said car, said means for registering calls include means at saidfloors for registering hall halls at said floors, and said availabilityindicating means also is controlled by said car call means and hasconditions dependent upon the number of car calls registered in a carand their floor position relation to registered hall calls.
 4. in adirection toward a car, opposite to the direction toward a car set forthin (2), the hall calls for service in said first direction and theavailability numbers of cars in said last-mentioned away direction; saidscanning means scanning the availability means and hall call registeringmeans in the numerical order of the floors at which cars and hall callsare located whereby the status of hall calls and the cars available toanswer such hall calls is substantially continuously indicated to thedispatching means for each operating car in the system.
 4. in the updirection to said car, the down hall calls and availability numbers forcars below said car; whereby the hall call registering means andavailability means are scanned in the order of their floor positionscommencing at each car upwardly to the highest floor, downwardly to thelowest floor and then upwardly to said last-mentioned car.
 4. thescanning shows, with respect to said answering car, that the number ofscanned hall calls below said answering car has a predetermined relationto the sum of the availability numbers corresponding to the availabilitymeans theretofore scanned for other cars located below said answeringcar.
 5. A system as set forth in claim 1 wherein said passengerresponsive means comprises car call registering means in each said carand said availability indicating means is controlled by said car callmeans and has different conditions dependent upon the number of carcalls registered in a car and their floor position relation toregistered hall calls.
 6. In an elevator system comprising a pluralityof elevator cars serving a plurality of floors, hall call means at saidfloors for registering calls at said floors, car call means in said carsfor registering calls for said floors, position means for each carcontrolled by the position of said car and direction means controlled bythe direction of movement in which a car is available to move, thecombination therewith of control means for controlling the movement ofsaid cars, said control means availability means for each car controlledby said car call means and said direction means for indicating theavailability of a car for movement in response to hall calls, saidavailability means having a plurality of conditions corresponding to theavailability of its associated car and to availability numbers asfollows:
 7. A system as set forth in claim 6 wherein N is equal to 2,said first predetermined number is equal to 1, said second predeterminednumber is equal to 2 and said predetermined relation is a number of saidhall calls greater than the sum of said availability numbers.
 8. Asystem as set forth in claim 6 further comprising load means for eachcar responsive to the load therein and wherein said availability meansis also controlled by said load means and said availability means alsohas said condition (3) and availability number zero when the loadexceeds a predetermined value.
 9. A system as set forth in claim 6wherein said control means in the absence of car calls holds each car atthe floor at which it stopped for its last call until the car isdirected to answer a hall call by said dispatch means.
 10. A system asset forth in claim 6 wherein one of said floors is a main floor andwherein said control means parks cars which are not answering hall orcar calls at floors within predetermined groups of floors and parks atleast one said car at a floor within a group of floors comprising apredetermined number of lower floors including said main floor, saidlast-mentioned number being less than about half the total number offloors.
 11. A system as set forth in claim 6 wherein said dispatchingmeans comprises a counter for each car, each such counter having meansfor adding an amount corresponding to said availability number and meansfor subtracting an amount corresponding to registered hall calls, anddirecting means responsive to said counter for directing a car to answerregistered hall calls whenever the sum algebraic of said availabilitynumbers and hall calls has a predetermined value and wherein saidscanning means supplies information as to availability numbers and hallcalls to each counter as follows:
 12. A system as set forth in claim 11wherein a car available for service is directed to answer a hall callfor service whenever the sum of availability numbers and the hall callsis less than zero and wherein said scanning means supplies informationas to availability numbers and hall calls to each counter as follows:13. A system as set forth in claim 11 wherein said dispatching meansfurther comprises modifying means for reducing the amount correspondingto an availability number added by a counter when the car correspondingto said last-mentioned counter has been directed to answer hall calls asa result of a hall call beyond another car available to move in thedirection of said last-mentioned hall call.
 14. A system as set forth inclaim 6 wherein one of said floors is the main floor and furthercomprising means for detecting down-peak traffic conditions and peaktraffic modifying means responsive thereto for modifying the operationof said system including means for selecting cars in a predeterminedorder of their arrival at the main floor to be ''''special'''' and''''normal'''' cars, means for preventing the scanning means fromsupplying to the dispatching means for ''''normal'''' cars informationas to condition of the availability means of upbound ''''special''''cars, means for preventing upbound ''''special'''' cars from answeringup hall calls above said main floor and means for preventing thescanning means from supplying to the dispatching means for upbound''''special'''' cars information as to the condition of the availabilitymeans of ''''normal'''' cars above.
 15. A system as set forth in claim14 wherein said modifying means further comprises means for recording apredetermined number of down hall calls in the time order ofregistration and means for preventing the scanning means from supplyingto the dispatching means for upbound ''''special'''' cars information asto down hall calls other than recorded down hall calls.
 16. A system asset forth in claim 14 wherein said modifying means further comprisesmeans for reducing the availability number of ''''special'''' cars. 17.A system as set forth in claim 14 further comprising means for detectingup-peak traffic conditions and wherein said modifying means is alsoresponsive to said last-mentioned means for modifying the operation ofsaid system and includes the following which operate when up-Peaktraffic conditions are detected:
 18. A system as set forth in claim 17wherein said modifying means further comprises means operable whenup-peak traffic conditions are detected, for causing up-peak''''normal'''' cars to reverse direction at floors other than said mainfloor when there is no demand for service therefor in said direction andthere is a demand for service in the opposite direction.
 19. A system asset forth in claim 17 wherein said means for detecting peak trafficconditions comprises means for counting the number of down hall calls,means for counting hall calls, means for totaling the car availabilitynumbers, means for comparing the number of hall calls with the sum ofthe car availability numbers, means for comparing the rate of car stopsfor car calls with the rate of car stops for down hall calls, and meansresponsive to said counting, totaling and comparing means for operatingsaid modifying means as follows:
 20. A system as set forth in claim 19wherein said predetermined relation for down-peak traffic and saidpredetermined relation for up-peak traffic are respectively hall callsgreater in number than and hall calls not greater in number than the sumof the car availability numbers.
 21. In an elevator system having aplurality of elevator cars serving a plurality of floors, means at saidfloors for registering calls for service from said floors, means in saidcars for registering calls for service to said floors and means forstopping said cars at floors for which calls are registered, thecombination therewith of means responsive to said registering means andsaid stopping means for comparing the rate of car stops for car callswith the rate of car stops for down hall calls and controlling meansresponsive to said comparing means for controlling the movement of saidcars.
 22. A system as set forth in claim 21 further comprising countingmeans for counting hall calls and wherein said controlling means is alsoresponsive to said counting means.
 23. A system as set forth in claim 22further comprising load means responsive to the load in said cars andavailability means responsive to said load means and said car callsmeans and wherein said controlling means is also responsive to saidavailability means.
 24. A system as set forth in claim 21 wherein one ofsaid floors is a main floor and wherein said controlling means isconditioned to dispatch cars so as to provide preferential service awayfrom said main floor when the ratio of the rate of car stops for carcalls to the rate of car stops for down hall calls is at least equal toa predetermined value and said controlling means is conditioned todispatch cars so as to provide preferential service toward said mainfloor when said ratio is less than said predetermined value.
 25. Asystem as set forth in claim 24 further comprising means for countinghall calls including down hall calls, availability means for each ofsaid cars, said availability means having different conditions dependentupon the directional availability of a car and the degree ofavailability of a car to answer hall calls, said conditionscorresponding to predetermined availability numbers, totaling meanscontrolled by said availability means for providing information as tothe sum of the car availability numbers, and means for comparing thenumber of hall calls with the sum of the car availability numbers, andwherein said controlling means is conditioned not only by the ratio ofthe rate of car stops for car calls to the rate of car stops for downhall calls but also by said counting, totaling and comparing means so asto provide control of said cars as follows:
 26. In an elevator systemhaving a plurality of cars serving a plurality of floors, car call meansin said cars operable by passengers therein for registering car callsfor said floors, hall call registering means at said floors operable byintending passengers for registering hall calls, position means for eachof said cars for providing information as to the positions of said carsand direction means for each of said cars for providing information asto the direction in which said cars are available to move, thecombination therewith of means for controlling the movement and parkingof said cars comprising availability means for each of said carsresponsive to said car call means and said direction means for providingelectrical signals corresponding to the directional and callavailability of the corresponding car; counter means for each of saidcars; scanning means; subtracting means responsive to said scanningmeans and to said hall call registering means for supplying subtractsignals to the counter for each car for hall calls above each car andalternately for hall calls below each car; adding means responsive tosaid scanning means and to said availability means for supplying addsignals to the counter for each car for cars above each car which areavailable to answer hall calls above each car and alternately for carsbelow each car which are available to answer hall calls below each car;reset means to reset said counter to a predetermined count conditionbetween the supplying of subtract signals for hall calls above and thesupplying of subtract signals of hall calls below to a counter; andcontrol means responsive to the counter for each car for causing the carcorresponding to a counter to answer hall calls when the count conditionof the corresponding counter is other than said predetermined countcondition just prior to resEtting of the counter for said last-mentionedcar and said last-mentioned car is in-service and capable of answeringhall calls.
 27. A system as set forth in claim 26 wherein said scanningmeans comprises code means for providing electrical signals in binarydigital code corresponding successively to each of said floors and thedirection of scanning with respect to the numerical order of the floorsand for providing, for each of the floors at which a car is positioned,electrical signals in binary digital code successively corresponding toeach of said cars; further comprising position code means for each ofsaid position means for providing electrical signals in binary digitalcode corresponding to the position of the corresponding car; furthercomprising parity means for each of said cars connected to said scanningmeans and said position code means for comparing the floor positionsignals of the corresponding car; wherein said control means comprisesmemory means for each of said cars, the memory means of each car beingoperable by said scanning means to cause said memory means to record ahall call at a floor at which the car is positioned; and said scanningmeans comprising operation means controlled by said parity means andcontrolling said availability means, said operation means being operablewhen said parity means indicates that there is a car at the floorposition of the scan of said scanning means for causing the followingoperations as to each car at said last-mentioned floor: a. reading bysaid memory means of the output of the car''s corresponding counter; b.supplying of an add signal from the availability means, if the car isavailable, to at least all of said counters for cars other than at saidlast-mentioned floor; c. resetting of the car''s counter to zero.
 28. Inan elevator system having a plurality of cars serving a plurality offloors, car call means in said cars operable by passengers therein forregistering car calls for said floors, hall call registering means atsaid floor operable by intending passengers for registering hall calls,position means for each of said cars for providing information as to thepositions of said cars and directions means for each of said cars forproviding information as to the direction in which said cars areavailable to move, the combination therewith of means for controllingthe movement and parking of said cars comprising position code means foreach of said position means for providing electrical signals in binarydigital code corresponding to the position of the corresponding car;first scanning means for providing electrical signals in binary digitalcode successively corresponding to each of said floors and the directionof scanning with respect to the numerical order of the floors, saidscanning means providing signals corresponding successively to thelowest and then higher floors and then providing signals correspondingsuccessively to the highest and then lower floors; three memory meansfor each of said cars, a first memory means for hall calls above thecars, a second memory means for hall calls below the car and a thirdmemory means for hall calls at the floor at which the corresponding caris located; a counter for each of said cars; parity means for each ofsaid cars connected to said first scanning means and said position codesmeans for comparing the floor position signals of the scan with thefloor position signals of the corresponding car; availability means foreach of said cars controlled by said direction means and said car callmeans of the corresponding car for providing electrical signalscorresponding to the directional and call availability of thecorresponding car; second scanning means operable by said first scanningmeans each time the scan of said first scanning means steps to adifferent floor, said first scanning means also being controlled by saidsecond scanning means and being stepped to a different floor aftercompletion of a scan by said second scanning Means; hall call comparingmeans connected to said scanning means, said hall call registering meansand said counters for providing a subtract signal to said counters whenthe first scanning means signals corresponds to the floor of the hallcall registering means and a hall call is registered thereat; saidsecond scanning means also controlling said third memory means of a carat said last-mentioned floor to cause said third memory means to recorda hall call which may be registered at said last-mentioned floor andsaid second scanning means being operable when said parity indicatesthat there is a car at the floor position of the scan of said firstscanning means for causing the following operations as to each car atsaid last-mentioned floor: a. reading by one of said first and secondmemory means, depending on the direction of movement of the scan of saidfirst scanning means, of the output of the car''s corresponding counter;b. supplying of an add signal from the availability means, if the car isavailable to at least all of said counters for cars other than at saidlast-mentioned floor; c. resetting of the car''s counter to zero; andcontrol means for each car responsive to said memories for causing thecorresponding car to move or park dependent upon the conditions of saidmemory means and the availability of the car.
 29. A system as set forthin claim 28 wherein said counters comprise means for preventing furtheraddition when the count therein is zero.
 30. A system as set forth inclaim 28 wherein said second scanning means causes said operations in apredetermined sequence with respect to said cars when a pluralitythereof are at the same floor other than a predetermined lower floor andwhen said first scanning means is scanning in the direction from lowerto upper floors and causes said operations in a sequence which isreversed with respect to said predetermined sequence when a plurality ofsaid cars are at the same floor other than said predetermined floor andsaid first scanning means is scanning in the direction from the upper tolower floors.
 31. In an elevator system comprising a plurality ofelevator cars serving a plurality of floors, car position meanscontrolled in accordance with the positions of said cars, car directionmeans controlled in accordance with the direction in which a car isavailable to move, call registering means for registering calls forservice by said cars for said floors, availability means controlled atleast by said car direction means for providing information as to theavailability of a car to answer registered calls, scanning means forsuccessively and repetitively scanning the information provided by saidcall registering means, said position means and said availability meansin a predetermined normal sequence for floors other than a predeterminedfloor, and controlling means responsive to said scanning means forcontrolling the movement of said cars dependent upon the number andrelative position of said calls to said cars and the availability ofcars to answer said calls, the combination therewith of selecting meansfor selecting a predetermined car at said predetermined floor andmodifying means controlled by said selecting means upon selection ofsaid predetermined car for modifying the operation of said scanningmeans in its scanning operation at said predetermined floor to provide ascanning sequence different from said normal sequence at saidpredetermined floor.
 32. The combination as set forth in claim 31wherein said scanning means, when modified in operation, scans withrespect to the selected car first when scanning the informationcorresponding to the direction in which said selected car is set to moveand scans with respect to the selected car last when scanning theinformation corresponding to the direction opposite to the direction inwhich said selected car is set to move.
 33. The combination as set forthin claim 32 wherein said selecting means selects the car next to departfrom said predetermined floor.
 34. In an elevator system comprising aplurality of elevator cars serving a plurality of floors, car positionmeans controlled in accordance with the positions of said cars, cardirection means controlled in accordance with the direction in which acar is available to move, call registering means for registering callsfor service by said cars for said floors, availability means controlledat least by said car direction means for providing information as to theavailability of a car to answer registered calls, means for successivelyand repetitively scanning on a continuous basis the information providedby said call registering means, said position means and saidavailability means, controlling means responsive to said scanning meansfor controlling the movement of said cars dependent upon the number andrelative positions of said calls to said cars and the availability ofcars to answer said calls, and automatic car shutdown means for removinga car from service when the demands for service therefor fall below apredetermined level, the combination therewith of modifying meansresponsive to said shutdown means for preventing response of thecontrolling means corresponding to a car which has not been shut down tothe scanning of information provided with respect to a car which hasbeen shut down and for modifying the response of the controlling meanscorresponding to a shutdown car.
 35. The combination as set forth inclaim 34 wherein the controlling means of a shutdown car, when modified,responds to said scanning means when it is scanning informationcorresponding to cars which have not been shut down and respondsdifferently in different scanning cycles to scanning informationcorresponding to shutdown cars.
 36. The combination as set forth inclaim 35 wherein during one scanning cycle, the controlling means of ashutdown car, when modified, responds to said scanning means when it isscanning information corresponding to shutdown cars located in apredetermined direction with respect to said shutdown car and does notrespond to said scanning means when it is scanning informationcorresponding to shutdown cars located in a direction opposite to saidpredetermined direction with respect to said shutdown car.
 37. A methodof controlling a plurality of elevator cars to serve a plurality offloors, comprising continuously providing bits of informationrepresenting some or all of hall calls and car position and availabilityto answer the calls, repetitively scanning on a continuous basis saidbits of information in a predetermined order and sufficiently rapidlythat the cars do not effectively change their positions during eachscan, and dispatching the cars in response to the scanned informationfrom wherever the cars happen to be, in which the hall call informationcomprises, for each floor, information as to up and down hall callsregistered from that floor, and the car position and availabilityinformation comprises, for each car, its availability to go up, itsavailability to go down, a car position corresponding to the nearestfloor for which the car is available, and the degree of availability ofthe car.
 38. A method as claimed in claim 37, in which the degree ofavailability of a car is the number of hall calls that the car isarbitrarily allowed to answer without requiring assistance from othercars.
 39. A method as claimed in claim 38, in which car calls and carloading are used to reduce the degree of availability of the car.
 40. Amethod as claimed in claim 37, in which the hall call information as todown hall calls at the various floors and the car position andavailability as to cars available to go down are scanned in ascendingorder from the lowest to the highest floor, and then the hall callinformation as to cars available to go up are scanned in descendingorder.
 41. A method as claimed in claim 40, in which for each floor thehall call information is scanned and then the car availabilityinFormation as to each car whose position is represented at that floor.42. A method as claimed in claim 41, in which the information as to onecar is scanned before the information as to another car whose positionis represented at the same floor.
 43. A method as claimed in claim 42,in which the predetermined order of scanning through the bits ofinformation indicating car availability is altered during that portionof the descending scan when conditions at the main floor are beingexamined, so that the bits of information representing the availabilityof the next up car are scanned first, before the corresponding bits ofinformation representing the availability of other cars, and in whichthe predetermined order of scanning through the bits of informationindicating car availability is altered during that portion of thedescending scan when conditions at the main floor are being examined, sothat the bits of information representing the availability of the nextup car are scanned last, after the corresponding bits of informationrepresenting the availability of other cars at the main floor have beenscanned.
 44. A method as claimed in claim 42, in which two consecutivebits of information are used to indicate a car''s degree ofavailability, one of them to indicate whether or not this car isavailable to answer two hall calls, and the other of them to indicatewhether or not this car is available to answer one hall call, so thatthe combination of these consecutive bits can indicate that this car isavailable to answer none, one, two or three hall calls.
 45. A method asclaimed in claim 44, in which each car is normally available to answertwo hall calls, but in which a car is available to answer only one hallcall if loaded beyond a predetermined load, or if an intervening carcall would require this car to make two stops before being able toanswer the second of two existing hall calls, and in which a car becomesunavailable if loaded beyond a higher predetermined load, or if twointervening car calls would require this car to make two stops beforeanswering an existing hall call.
 46. A method as claimed in claim 45, inwhich it is determined whether there are hall calls above a car whichthe car should answer by resetting a counter at a point in the ascendingscan during scanning of the conditions at the floor where the car isrepresented to be, by subtracting one each time a hall call is scanned,by adding two each time a car with an availability of two is scanned, bynever allowing the accumulated count on the counter to be a positivenumber, and by reading the accumulated count on the counter at a pointin the descending scan during scanning of the conditions at the floorwhere the car is represented to be, and in which a negative accumulatedcount is an indication that there are hall calls above, which this carshould answer; and in which it is determined whether there are hallcalls below a car which the car should answer by resetting a counter ata point in the descending scan during scanning of conditions at thefloor where the car is represented to be, by subtracting one each time ahall call is scanned, by adding one each time a car with an availabilityof one is scanned, by adding two each time a car with an availability oftwo is scanned, by never allowing the accumulated count to be a positivenumber, and by reading the accumulated count on the counter at a pointin the descending scan during scanning of the conditions at the floorwhere the car is represented to be, and in which a negative accumulatedcount is an indication that there are hall calls below, which this carshould answer.
 47. A method as claimed in claim 46, in which when the updirection of travel is established for a car, and when there are no hallcalls below it which it should answer, its counter adds one, instead oftwo, each time a car above with an availability of two is seen duringthe scan; and when the down direction of travel is established for acar, and when There are no hall calls above it which it should answer,its counter adds one, instead of two, each time a car below with anavailability of two is seen during the scan.
 48. A method as claimed inclaim 46, in which cars whose MG sets are running do not respond to thebits of information regarding the availability of cars whose MG sets areshut down automatically, and in which for each car whose MG set isautomatically shut down it is determined when there are hall calls aboveit, which require it to start its MG set in order to answer some or allof these hall calls, be resetting a counter at a point in the descendingscan during scanning of the conditions at the floor where the car isrepresented to be, by subtracting one each time a hall call is scanned,by adding one each time a car with an availability of one, and whose MGset is running, is scanned, by adding two each time a car with anavailability of two is scanned, whose MG set is running, by allowing theaccumulated count to be a positive number as well as a negative number,by continuing this counting until a point in the ascending scan isreached where the conditions at the floor where the car is representedto be is being scanned, by resetting the counter at this point only ifthe accumulated count on the counter is negative, by continuing tosubtract one each time a hall call is scanned, by adding one each time acar with an availability of one is scanned, provided that theaccumulated count is negative or that the car has its MG set running, byadding two each time a car with an availability of two is scanned,provided that the accumulated count is negative or that the car has itsMG set running, and by not allowing such addition of two to take theaccumulated count from a negative number to beyond zero except for a carwhose MG set is running, and by reading the accumulated count on thecounter at a point in the descending scan when conditions at the floorwhere the car is represented to be are being scanned, and in which anegative accumulated count is an indication that this car should startits MG set, and go up to answer hall calls above; and in which for eachcar whose MG set is automatically shut down it is determined when thereare hall calls below it, which require it to start its MG set in orderto answer some or all of these hall calls, by resetting a counter at apoint in the ascending scan during scanning of the conditions at thefloor where the car is represented to be, by subtracting one each time ahall call is scanned, by adding one each time a car with an availabilityof one, and whose MG set is running, is scanned, by adding two each timea car with an availability of two is scanned, whose MG set is running,by allowing the accumulated count to be a positive number as well as anegative number, by continuing this counting until a point in thedescending scan reached where the conditions at the floor where the caris represented to be are being scanned, by resetting the counter at thispoint only if the accumulated count on the counter is negative, bycontinuing to subtract one each time a hall call is scanned, by addingone each time a car with an availability of one is scanned, providedthat the accumulated count is negative or that the car has its MG setrunning, by adding two each time a car with an availability of two isscanned, provided that the accumulated count is negative or that the carhas its MG set running, and by not allowing each addition of two to takethe accumulated count from a negative number to beyond zero except for acar whose MG set is running, and by reading the accumulated count on thecounter at a point in the ascending scan when conditions at the floorwhere the car is represented to be are being scanned, and in which anegative accumulated count is an indication that this car should startits MG set, and go down to answer hall calls below.
 49. A method asclaimed in claim 37, in which the floors are divided intO at least fourgroups of floors of which the lowest group contains the main floor, andin which cars are distributed throughout the building, when nototherwise required for the answering of car or hall calls, such that, aslong as a predetermined number of cars more than one are available, inthe absence of cars in the lowest group of floors the lowest car isbrought down to the main floor, in the absence of cars in the upper twogroups of floors the highest car travels up until it is at the lowestfloor of the upper group of floors, in the absence of cars in anyintermediate two immediately adjacent groups of floors the lowest car ina group of floors above the two adjacent groups, provided that there aretwo or more such cars there, travels down until it is at the top floorof the lower of these two intermediate adjacent groups of floors, or, ifthere are less than two cars in the group of floors, above the twoadjacent groups, and there are no cars in the two intermediate adjacentgroups of floors, the highest car in a group of floors below the twoadjacent groups travels up until it is at the bottom floor of the higherof these two intermediate adjacent groups of floors, provided that thereare at least two cars in the lowest group of floors.
 50. A method asclaimed in claim 37, in which the floors are divided into four groups offloors of which the lowest group contains the main floor, and in whichcars whose MG sets are running are distributed throughout the building,when not otherwise required for the answering of car or hall calls, suchthat, as long as two or more cars have their MG sets running, in theabsence of cars with MG sets running in the lowest group of floors thelowest car with MG set running is brought down to the main floor, in theabsence of cars with MG sets running in the upper two groups of floorsthe highest car with MG set running travels up until it is at the lowestfloor of the upper group of floors, in the absence of cars with MG setsrunning in the middle two groups of floors the lowest car with MG setrunning in the upper group of floors, provided that there are two ormore such cars there, travels down until it is at the top floor of thelower of these two middle groups of floors, or, if there are less thantwo cars with MG sets running in the upper group of floors, and thereare no cars with MG sets running in the middle two groups of floors, thehighest car with MG set running in the lowest group of floors travels upuntil it is at the bottom floor of the higher of these two middle groupsof floors, provided that there are at least two cars with MG setsrunning in the lowest group of floors.
 51. A method as claimed in claim37, in which the order of registration of down hall calls, for floorsabove the main floor, is continuously recorded, and in which, duringdown-peak, one group of cars answers long-wait down hall calls, andanother group of cars answers other calls including up hall calls.
 52. Amethod as claimed in claim 51, in which, upon arrival at the main floorduring down peak, cars are allocated to said one group and remain insaid one group only until they commence their next down trip, cars notso allocated and all cars in their down trip belonging to said othergroup.
 53. A method as claimed in claim 52, in which the allocation ofcars to said one group or to said other group upon arrival at the mainfloor follows a predetermined sequence independent of whether a car haspreviously been allocated to said one group.
 54. A method as claimed inclaim 53, in which the number of calls treated as long-wait calls equalsthe number of cars allocated to said one group.